So, not until recently have I had the time to methodically work on "buttoning-up" this project. Using USALS, I have Mex6 (Eutelsat 113 West A at 113.0°W) as my Reference "southern bird". Using Titanium C1W-PLL with a Conical Scaler.
Here is my odd issue, when I point dish to birds east of Mex 6 I can lock onto Vertical TPs, but unable to lock onto them west of my reference bird.
We're talking about C-band on a 1.2m dish. Which vertical tps in particular do you expect to receive which you aren't? West of 113W, I don't receive many tps at all. The stronger C-band tps seem to be east of 113W such as on 105W, 99W, 97W and 91W.
Here are vertical tps you probably should be able to receive assuming your dish can see these satellites. On 118.8W: Weather Network on 4096 V 23800, Legislative Assembly of Ontario on 4116 V 3399, EMF radio mux on 4196 V 2800. On 127W, NASA on 3920 V 28068.